Anatomy and Structural Connectivity of the Opercula

Summary:

The cerebral operculum comprises the cortical folds of the frontal, central, parietal, and temporal lobes that overlie the insula. Although historically described as a simple anatomical “cover,” the operculum is now recognized as a morphologically complex periSylvian region embedded within multiple cortico-cortical and cortico-subcortical networks. In this review, a comprehensive synthesis of opercular organization is provided, integrating topographic anatomy, structural connectivity, and vascular supply. The topographic anatomy of the operculum is described in relation to periSylvian sulcal landmarks that define four opercular subregions—the frontal, rolandic (i.e., central), parietal, and temporal opercula—and to the outer Sylvian membrane, which separates the superficial from the medial operculum. Structural connectivity involves well-defined major white matter tracts—including the superior longitudinal, arcuate, inferior fronto-occipital, uncinate, and middle longitudinal fasciculi—alongside operculum-specific associative connections, commissural pathways, and projection fibers. Within this structural framework, the operculum emerges as a critical hub in language, auditory, visual, and gustatory networks, supporting multimodal integration and higher-order processing. Cortical and white matter vascularization of the opercular region is dominated by centripetal branches arising from the M2 to M4 segments of the middle cerebral artery, which supply both superficial and deeper opercular layers. Collectively, the complex morphology, dense structural connectivity, and complex vascular organization of the operculum provide a structural basis for its functional importance and help explain the clinical heterogeneity of opercular epilepsy, including the challenges associated with its diagnosis and surgical management.